1. Field of the Invention
The present invention relates to a speaker having an improved sound-radiating function to both directions.
2. Description of the Related Art
A speaker is an audio apparatus for radiating sound waves, which are compression-rarefaction waves propagating through air used for a medium, by converting electrical sound signals into vibrations of a vibrating plate and compressing and expanding air using the vibrations of the vibrating plate.
A related art speaker will be described with reference to FIG. 1, which is a sectional view of a related art speaker.
As illustrated in FIG. 1, a speaker 10 includes a cone-shaped frame 20, a magnetic circuit unit 30 coupled to the frame 20, and a vibration unit 40.
The magnetic circuit unit 30 has a U-shaped yoke 31 whose upper portion is coupled to one side of the frame 20, and a magnet 33 and a pole piece 35 sequentially stacked and coupled in an inside of the yoke 31. At this point, a predetermined interval is interposed between an outer periphery of the magnet 33 and the pole piece 35 and an inner periphery of the yoke 31. The vibration unit 40 includes: a vibrating plate 41 having a coupling hole formed on a central portion of the vibrating plate 41 and whose outer periphery is coupled to the other side of the frame 20; and a voice coil 43 whose one end is coupled to the coupling hole and whose other end is disposed in the interval between the pole piece 35 and the yoke 31.
With such a construction, if an external voltage is applied to the voice coil 43, the voice coil 43 operates due to interaction between an electric field from the voice coil 43 and a magnetic field from the magnetic circuit unit 30 to vibrate the vibrating plate 41. Then, air contacting a surface of the vibrating plate 41 compresses and expands. due to the vibrations of the vibrating plate 41, so that a sound is produced. Unexplained reference numerals 51, 53, and 55 are a damper, a dust cap, and a gasket, respectively.
Since the related art speaker has the cone-shaped vibrating plate 41, much difference has occurred between a sound radiated to a forward direction where a diameter of the speaker is large and a sound radiated to a backward direction where a diameter of the speaker is small.
Also, since a sound radiated to the backward direction has been shielded due to the damper 51 and the magnetic circuit unit 30 installed at the rear side of the vibrating plate 41, such a difference in sounds has become severe.